The two bottles for the purification of the gas mixture intended for a cryogenic separation device operate in a cyclic manner between high-pressure adsorption phases and low-pressure regeneration phases. The transition between regeneration and adsorption therefore requires a pressurization of the bottle with feed gas from the cold box. This additional flow must be supplied by the main air compressor for air separation units. This therefore makes it necessary to size this compressor for the nominal flow increased by this bottle pressurization flow.
For air separation units without the production of argon, it may be accepted that the pressurization of the bottles is carried out to the detriment of the feed flow from the cold box without significant stability problems for the columns.
For separation units with argon production, the flow disturbance is too severe not to specify the compressor without this additional flow.
It is known to compensate for the reduction in the airflow by regulating the flows of reflux liquid (U.S. Pat. No. 6,073,463).